1. Field of the Invention
This invention relates to Liquified Petroleum Gas (LPG) fueled internal combustion engine powered arrangements and, more particularly, to such arrangements in which the internal combustion engine is powered by the gas phase of the LPG at all times and may be as utilized in lawnmowers, weed whackers, leaf blowers, string trimmers and the like
2. Description of the Prior Art
Utilization of LPG as a fuel for internal combustion engines has been heretofore been known for use in large internal combustion engine powered arrangements such as forklifts, trucks, buses and other such arrangements and devices. As such, the tank capacity of the LPG is quite large: on the order of 5 gallons or larger and in which the LPG is withdrawn from the LPG tank in liquid phase form and this requires that the LPG tanks be mounted in a particular orientation so that only liquid phase LPG is withdrawn therefrom during operation of the internal combustion engine 12. Further, the LPG tank is, generally, mounted in regions remote from the engine or any normally occurring heat source during operation and/or storage of the device.
During operation of such devices, the liquid phase LPG travels through transfer lines to either a vaporizer or a vaporizer/regulator structure. The vaporizer or vaporizer/regulator causes the liquid phase LPG to be converted to the gas phase LPG. The latent heat of vaporization of the liquid phase LPG as it is converted to the gas phase LPG would cause the vaporizer or vaporizer/regulator to get extremely cold and in many applications would freeze the liquid phase LPG to a solid phase and thus stop the flow of LPG to the engine unless means are provided to heat the vaporizer or vaporizer/regulator. Various structural arrangements have heretofore been utilized to supply heat to the vaporizer or vaporizer/regulator. In liquid cooled internal combustion engines the hot engine coolant was often routed to pass through or adjacent to the vaporizer or vaporizer/regulator in order to transfer heat thereto. In air cooled internal combustion engines some or all of the hot exhaust products may be forced over the vaporizer or vaporizer/regulator by the engine cooling fan. In other prior art applications, the LPG transfer lines may be placed in close proximity to the exhaust manifold or the vaporizer or vaporizer/regulator may be close coupled to the exhaust manifold for receiving heat therefrom.
In yet other prior art devices, an electrically powered heater was provided at the vaporizer or vaporizer/regulator.
Thus, such prior art applications and devices utilizing the large tanks of LPG often required many complex structural arrangements and components in order to insure that the liquid phase LPG was converted to the gas phase LPG.
In many other applications, the use of a large, e.g., 5 gallon LPG tank and its attendant complexity is not needed or desired. For example, in many smaller internal combustion engine powered devices, it is often desired to utilize a small LPG tank such as one containing one or two pounds of LPG. Such devices include, but are not limited to lawnmowers, leaf blowers, string trimmers, or the like. The one or two pound LPG tanks are readily available as such LPG tanks are widely utilized in the camping industry to provide LPG for portable for stoves, lamps and the like. However, in such applications, the LPG tank is oriented to provide that only the gas phase LPG exits the LPG tank and, therefore, the freezing of the LPG would occur in the LPG tank rather than external the LPG tank. Depending on the rate of flow of the gas phase LPG from the LPG tank, the freezing of the LPG occurs in the LPG tank.
However, in many applications it is desired that the mounting of the LPG tank be such that no specific orientation of the LPG tank is required for the internal combustion engine to operate on the gas phase of the LPG.
Accordingly, there has long been a need to provide an LPG fueled internal combustion engine apparatus utilizing propane as the LPG from a conventional one to two pound LPG propane tank for the supply of the LPG and which does not require a particular orientation of the LPG tank with respect to gravity for satisfactory operation. Additionally, many of the prior art LPG fueled internal combustion engine powered devices have utilized butane as the LPG. Such devices are common in many foreign countries such as Japan and Korea. In the United States and in Europe, on the other hand, propane LPG tanks are quite readily available. The physical properties of propane as compared to butane makes the propane LPG tanks more attractive as a fuel for the small internal combustion engine applications. For example, for an equivalent amount of LPG, a butane fueled device would run for about one half hour while for a propane fueled device would run for about three to four hours. Also, the butane LPG tanks that are readily available in Japan and Korea provide for only gas phase butane to be withdrawn from the bottle and are provided with an internal tube to insure that only gas is withdraw and thus require a preferred orientation with respect to gravity. Since liquid phase butane becomes a gas phase butane at about 31 degrees F. which is only about 39 degrees F. different from the conventionally stated standard operating temperature of a nominal 70 degrees F., there is little cooling effect due to the evaporation of the gas. Freezing in the LPG tank or in the system is not likely by utilization in a small internal combustion engine. Liquid phase propane, on the other hand, becomes gas phase propane at about minus 44 degrees F. which is about 114 degrees F. different from the conventionally stated standard operating temperature of a nominal 70 degrees F. Therefore, the propane would freeze to the solid phase in the LPG tank or elsewhere in the delivery system long before the LPG tank is empty depending on the consumption rate and the temperature. As contrasted to butane, the propane requires structure to prevent freezing to the solid phase.
Therefore, it is an object of the present invention to provide an LPG fueled internal combustion engine apparatus utilizing propane as the LPG.
It is another object of the present invention to utilize a conventional one to two pound LPG propane tank for the supply of the LPG.
It is another object of the present invention to provide an LPG fueled internal combustion engine apparatus utilizing propane as the LPG and in which the propane is provided from a conventional one to two pound LPG propane tank for the supply of the LPG.
It is another object of the present invention to provide an LPG fueled internal combustion engine apparatus utilizing propane as the LPG from a conventional one to two pound LPG propane tank for the supply of the LPG and which does not require a particular orientation of the LPG tank with respect to gravity for satisfactory operation.
It is another object of the present invention to provide an LPG fueled internal combustion engine apparatus utilizing propane as the LPG from a conventional one to two pound LPG propane tank for the supply of the LPG which does not require a particular orientation of the LPG tank with respect to gravity for satisfactory operation and in which the possibility of freezing of the liquid phase LPG to the solid phase LPG is substantially prevented in both the LPG tank and in the gas phase supply system to the internal combustion engine.
It is yet another object of the present invention to provide an LPG fueled internal combustion engine apparatus utilizing propane as the LPG from a conventional one to two pound LPG propane tank for the supply of the LPG which does not require a particular orientation of the LPG tank with respect to gravity for satisfactory operation and which insures that only gas phase LPG propane is withdrawn from the LPG tank regardless of the orientation thereof during operation.